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Title: Time-lapse VSP data processing for monitoring CO2 injection

Journal Article · · The Leading Edge
OSTI ID:973176
 [1];  [1];  [2]
  1. Los Alamos National Laboratory
  2. CAMBRIDGE GEOSCIENCES

As a part of the effort of the Southwest Regional Partnership on Carbon Sequestration supported by U.S. Department of Energy and managed by the National Energy Technology Laboratory, two sets of time-lapse VSPs were acquired and processed in oil fields undergoing CO{sub 2} injection. One set of VSPs was acquired at the Aneth oil field in Utah, the other set at the Scurry Area Canyon Reef Operators Committee (SACROC) field in West Texas. One baseline and two repeat VSP surveys were conducted from 2007 to 2009 at the Aneth oil field in Utah for monitoring CO{sub 2} injection. The aim of the time-lapse VSP surveys is to study the combined enhanced oil recovery (EOR) and CO{sub 2} sequestration in collaboration with Resolute Natural Resources, Inc. VSP data were acquired using a cemented geophone string with 60 levels at depth from 805 m to 1704 m, and CO{sub 2} is injected into a horizontal well nearby within the reservoir at depth approximately from 1730 m to 1780 m. For each VSP survey, the data were acquired for one zero-offset source location and seven offset source locations (Figure 1). The baseline VSP survey was conducted before the CO{sub 2} injection. More than ten thousand tons of CO{sub 2} was injected between each of the two repeat VSP surveys. There are three horizontal injection wells, all originating from the same vertical well. One is drilled towards Southeast, directly towards the monitoring well (Figure 2), and the other two towards Northwest, directly away from the monitoring well. The injection is into the top portion of the Desert Creek formation, just beneath the Gothic shale, which acts as the reservoir seal. The initial baseline acquisition was done in October 2007; subsequent time-lapse acquisitions were conducted in July 2008, and January 2009. The acquisition geometry is shown in Figure 1. Shot point 1 is the zero-offset source location, Shot points 2 to 8 are the seven offset VSPs, arranged in a quarter circle on the Northwest side of the monitoring well. The horizontal injection well is shown in green. The black lines in Figure 1 show the approximate reflection coverage al reservoir depth from the respective offset source locations. VSP source location 5 is in a direct line with the injection. The 60 geophone sondes were cemented into the monitor well just before the baseline VSP acquisition and consisted of 96 geophone channels, with 18 three-component geophones (at the bottom of the string) and 42 single vertical component phones above. For this study, only the vertical geophone data were used.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC52-06NA25396
OSTI ID:
973176
Report Number(s):
LA-UR-09-06751; LA-UR-09-6751; TRN: US201006%%299
Journal Information:
The Leading Edge, Journal Name: The Leading Edge
Country of Publication:
United States
Language:
English